The present invention is directed generally to heat transport systems. More particularly, the present invention is directed to heat transport apparatus having loop heat pipes.
A disadvantage of using a heat transport system having only a single loop heat pipe is that failure of that pipe would greatly impact operation. In many space applications in particular, there would be no backup system to transport heat. A solution to the problem of failure of a single pipe is redundancy.
Redundant designs are of particular value for space applications because the space environment can be very harsh. For example, there is potential for damage to or failure of parts due to micrometeoroids. Also, the longevity of space craft missions (typically 15 years) without the possibility of servicing in geosynchronous orbit makes reliability critical.
Conventional redundancy in the case of loop heat pipes, however, requires apparatus that is heavy, large, and expensive to manufacture.
Some loop heat pipes comprise an evaporator and a condenser, both of which have a saddle. In some typical single loop heat pipe systems, the evaporator saddle has four flanges and the condenser saddle has two flanges. A conventional redundant heat transport apparatus has two loop heat pipes for redundancy. The apparatus has first and second evaporator saddles for the first and second loop heat pipes, respectively. Also, the apparatus has first and second condenser saddles for the first and second loop heat pipes, respectively. Conventional redundant heat transport apparatus comprising two typical single loop heat pipes thus have a total of eight flanges associated with the evaporator saddles and a total of four flanges associated with the condenser saddles, the flanges being very heavy and consuming a lot of space.
Redundancy, minimum weight, and small mechanical envelope (i.e., small volume or space consumption) are particularly desirable in space applications. Thus, there is a need for a redundant heat transport apparatus which has reduced weight and requires less space than a conventional redundant heat transport apparatus. There is also a need for redundant heat transport apparatus having reduced manufacturing costs.
Heat transfer apparatus having redundant constant conductance heat pipes (CCHPs), also called fixed conductance heat pipes (FCHPs), have been utilized in space applications. Such apparatuses comprise an evaporator saddle that accommodates two evaporators, and a condenser saddle that accommodates two condensers. The redundant CCHP (or FCHP) only has four flanges extending from the evaporator saddle and two flanges extending from the condenser saddle.
However, CCHPs have grooves extending longitudinally on the inner surface of the pipes which make the pipes rigid. Also, CCHPs are orientation sensitive and do not function very effectively in gravity. Thus, there is a need for a flexible redundant heat transport apparatus. There is also a need for a heat transport apparatus suitable for applications, such as terrestrial applications, where there is gravity.